On Wed, Apr 29, 2020 at 11:42 AM Christoph Hellwig <hch@xxxxxx> wrote: > > On Wed, Apr 29, 2020 at 10:07:11AM +0200, Arnd Bergmann wrote: > > > What do you think of this version? This one always overrides > > > copy_siginfo_to_user32 for the x86 compat case to keep the churn down, > > > and improves the copy_siginfo_to_external32 documentation a bit. > > > > Looks good to me. I preferred checking for X32 explicitly (so we can > > find and kill off the #ifdef if we ever remove X32 for good), but there is > > little difference in the end. > > Is there any realistic chance we'll get rid of x32? When we discussed it last year, there were a couple of users that replied saying they actively use it for a full system, and some others said they run specific programs built as x32 as it results in much faster (10% to 20%) execution of the same binaries compared to either i686 or x86_64. I expect both of these to get less common over time as stuff bitrots and more of the workloads that benefit most from the higher performance (cross-compilers, hpc) run out of virtual address space. Debian popcon numbers are too small to be reliable but they do show a trend at https://popcon.debian.org/stat/sub-x32.png I would just ask again every few years, and eventually we'll decide it's not worth keeping any more. I do expect most 32-bit machines to stop getting kernel updates before 2030 and we can probably remove a bunch of architectures including x32 before then, though at least armv7 users will have to get kernel updates for substantially longer. Arnd
